LM51561: Flyback controller selection - LM51561

mahesh gohil

Part Number: LM51561
Other Parts Discussed in Thread: LM51551, LM5156

Hello,

We are working in PSE design and selecting the components. We have selected LM51561 as boost controller. Our design requirements are,

Vin-18V to 32V DC

Vout -54V,1A (60W) for POE ports

Our questions are,

1) Is the selected controller is best for the application or there is any other suggestion ? How is it different than LM51551 ? Only input voltage rating?

2) Need help to derive transformer design parameter

3) Can u pls suggest 4 x Port type1 PSE

over 4 years ago

0 Brigitte over 4 years ago

TI__Guru 66350 points

Hello mahesh,

You mention above that you are planning to use LM51561 as boost converter.

1. For your application, LM5155x or LM5156x are the best fitting devices, I think. The difference is the input voltage and the LM5156x family has as well the dithering feature.

2. Why do you need a transformer?

3. Please start a different thread for this as this is a different group in TI.

Best regards,
Brigitte

0 mahesh gohil over 4 years ago

Prodigy 190 points

Hello Brigitte,

1) We are planning to use - LM5156x in flyback boost mode.

2) we need the flyback isolated power. So need the flayback transformer

3) Can you please suggest or share a link to post this query at appropriate forum.

0 Brigitte over 4 years ago in reply to mahesh gohil

TI__Guru 66350 points

Hello mahesh,

Sorry for the misunderstanding.

I think a good starting point for the transformer design is the power stage designer software: https://www.ti.com/tool/POWERSTAGE-DESIGNER

This tool helps to design the power stage of a lot different topologies, including the flyback transformer.

Then if you calculated the transformer you want to use, the quickstart calculator for LM5156 helps to calculate all the other components in detail: https://www.ti.com/lit/zip/snvc240

You might as well have a look into this app note: https://www.ti.com/lit/an/snva866/snva866.pdf

For the question about the 4 port type 1 PSE, the switches and multiplexers forum should be the right one: https://e2e.ti.com/support/switches-multiplexers-group/switches-multiplexers/f/switches-multiplexers-forum

But even if you put the other thread in the wrong forum, it will find its way to the right team. I just cannot forward this thread to another forum as I did not answer your other questions. Sorry.

Best regards,
Brigitte

0 Brigitte over 4 years ago in reply to Brigitte

TI__Guru 66350 points

Hello mahesh,

As I did not heard back from you, I expect you have been able to solve your issue and will close this thread now. If this is not the case, please post below or start a new thread if this one is already locked.

Best regards,
Brigitte

Power management

Power management forum

LM51561: Flyback controller selection - LM51561